+++ /dev/null
-/* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
- *
- * probes/lttng-kretprobes.c
- *
- * LTTng kretprobes integration module.
- *
- * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- */
-
-#include <linux/module.h>
-#include <linux/kprobes.h>
-#include <linux/slab.h>
-#include <linux/kref.h>
-#include <lttng/events.h>
-#include <ringbuffer/frontend_types.h>
-#include <wrapper/vmalloc.h>
-#include <wrapper/irqflags.h>
-#include <lttng/tracer.h>
-#include <blacklist/kprobes.h>
-
-enum lttng_kretprobe_type {
- EVENT_ENTRY = 0,
- EVENT_RETURN = 1,
-};
-
-struct lttng_krp {
- struct kretprobe krp;
- struct lttng_event *event[2]; /* ENTRY and RETURN */
- struct kref kref_register;
- struct kref kref_alloc;
-};
-
-static
-int _lttng_kretprobes_handler(struct kretprobe_instance *krpi,
- struct pt_regs *regs,
- enum lttng_kretprobe_type type)
-{
- struct lttng_krp *lttng_krp =
- container_of(krpi->rp, struct lttng_krp, krp);
- struct lttng_event *event =
- lttng_krp->event[type];
- struct lttng_probe_ctx lttng_probe_ctx = {
- .event = event,
- .interruptible = !lttng_regs_irqs_disabled(regs),
- };
- struct lttng_channel *chan = event->chan;
- struct lib_ring_buffer_ctx ctx;
- int ret;
- struct {
- unsigned long ip;
- unsigned long parent_ip;
- } payload;
-
- if (unlikely(!READ_ONCE(chan->session->active)))
- return 0;
- if (unlikely(!READ_ONCE(chan->enabled)))
- return 0;
- if (unlikely(!READ_ONCE(event->enabled)))
- return 0;
-
- payload.ip = (unsigned long) krpi->rp->kp.addr;
- payload.parent_ip = (unsigned long) krpi->ret_addr;
-
- lib_ring_buffer_ctx_init(&ctx, chan->chan, <tng_probe_ctx, sizeof(payload),
- lttng_alignof(payload), -1);
- ret = chan->ops->event_reserve(&ctx, event->id);
- if (ret < 0)
- return 0;
- lib_ring_buffer_align_ctx(&ctx, lttng_alignof(payload));
- chan->ops->event_write(&ctx, &payload, sizeof(payload));
- chan->ops->event_commit(&ctx);
- return 0;
-}
-
-static
-int lttng_kretprobes_handler_entry(struct kretprobe_instance *krpi,
- struct pt_regs *regs)
-{
- return _lttng_kretprobes_handler(krpi, regs, EVENT_ENTRY);
-}
-
-static
-int lttng_kretprobes_handler_return(struct kretprobe_instance *krpi,
- struct pt_regs *regs)
-{
- return _lttng_kretprobes_handler(krpi, regs, EVENT_RETURN);
-}
-
-/*
- * Create event description
- */
-static
-int lttng_create_kprobe_event(const char *name, struct lttng_event *event,
- enum lttng_kretprobe_type type)
-{
- struct lttng_event_field *fields;
- struct lttng_event_desc *desc;
- int ret;
- char *alloc_name;
- size_t name_len;
- const char *suffix = NULL;
-
- desc = kzalloc(sizeof(*event->desc), GFP_KERNEL);
- if (!desc)
- return -ENOMEM;
- name_len = strlen(name);
- switch (type) {
- case EVENT_ENTRY:
- suffix = "_entry";
- break;
- case EVENT_RETURN:
- suffix = "_return";
- break;
- }
- name_len += strlen(suffix);
- alloc_name = kmalloc(name_len + 1, GFP_KERNEL);
- if (!alloc_name) {
- ret = -ENOMEM;
- goto error_str;
- }
- strcpy(alloc_name, name);
- strcat(alloc_name, suffix);
- desc->name = alloc_name;
- desc->nr_fields = 2;
- desc->fields = fields =
- kzalloc(2 * sizeof(struct lttng_event_field), GFP_KERNEL);
- if (!desc->fields) {
- ret = -ENOMEM;
- goto error_fields;
- }
- fields[0].name = "ip";
- fields[0].type.atype = atype_integer;
- fields[0].type.u.integer.size = sizeof(unsigned long) * CHAR_BIT;
- fields[0].type.u.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT;
- fields[0].type.u.integer.signedness = lttng_is_signed_type(unsigned long);
- fields[0].type.u.integer.reverse_byte_order = 0;
- fields[0].type.u.integer.base = 16;
- fields[0].type.u.integer.encoding = lttng_encode_none;
-
- fields[1].name = "parent_ip";
- fields[1].type.atype = atype_integer;
- fields[1].type.u.integer.size = sizeof(unsigned long) * CHAR_BIT;
- fields[1].type.u.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT;
- fields[1].type.u.integer.signedness = lttng_is_signed_type(unsigned long);
- fields[1].type.u.integer.reverse_byte_order = 0;
- fields[1].type.u.integer.base = 16;
- fields[1].type.u.integer.encoding = lttng_encode_none;
-
- desc->owner = THIS_MODULE;
- event->desc = desc;
-
- return 0;
-
-error_fields:
- kfree(desc->name);
-error_str:
- kfree(desc);
- return ret;
-}
-
-int lttng_kretprobes_register(const char *name,
- const char *symbol_name,
- uint64_t offset,
- uint64_t addr,
- struct lttng_event *event_entry,
- struct lttng_event *event_return)
-{
- int ret;
- struct lttng_krp *lttng_krp;
-
- /* Kprobes expects a NULL symbol name if unused */
- if (symbol_name[0] == '\0')
- symbol_name = NULL;
-
- ret = lttng_create_kprobe_event(name, event_entry, EVENT_ENTRY);
- if (ret)
- goto error;
- ret = lttng_create_kprobe_event(name, event_return, EVENT_RETURN);
- if (ret)
- goto event_return_error;
- lttng_krp = kzalloc(sizeof(*lttng_krp), GFP_KERNEL);
- if (!lttng_krp)
- goto krp_error;
- lttng_krp->krp.entry_handler = lttng_kretprobes_handler_entry;
- lttng_krp->krp.handler = lttng_kretprobes_handler_return;
- if (symbol_name) {
- char *alloc_symbol;
-
- alloc_symbol = kstrdup(symbol_name, GFP_KERNEL);
- if (!alloc_symbol) {
- ret = -ENOMEM;
- goto name_error;
- }
- lttng_krp->krp.kp.symbol_name =
- alloc_symbol;
- event_entry->u.kretprobe.symbol_name =
- alloc_symbol;
- event_return->u.kretprobe.symbol_name =
- alloc_symbol;
- }
- lttng_krp->krp.kp.offset = offset;
- lttng_krp->krp.kp.addr = (void *) (unsigned long) addr;
-
- /* Allow probe handler to find event structures */
- lttng_krp->event[EVENT_ENTRY] = event_entry;
- lttng_krp->event[EVENT_RETURN] = event_return;
- event_entry->u.kretprobe.lttng_krp = lttng_krp;
- event_return->u.kretprobe.lttng_krp = lttng_krp;
-
- /*
- * Both events must be unregistered before the kretprobe is
- * unregistered. Same for memory allocation.
- */
- kref_init(<tng_krp->kref_alloc);
- kref_get(<tng_krp->kref_alloc); /* inc refcount to 2, no overflow. */
- kref_init(<tng_krp->kref_register);
- kref_get(<tng_krp->kref_register); /* inc refcount to 2, no overflow. */
-
- /*
- * Ensure the memory we just allocated don't trigger page faults.
- * Well.. kprobes itself puts the page fault handler on the blacklist,
- * but we can never be too careful.
- */
- wrapper_vmalloc_sync_mappings();
-
- ret = register_kretprobe(<tng_krp->krp);
- if (ret)
- goto register_error;
- return 0;
-
-register_error:
- kfree(lttng_krp->krp.kp.symbol_name);
-name_error:
- kfree(lttng_krp);
-krp_error:
- kfree(event_return->desc->fields);
- kfree(event_return->desc->name);
- kfree(event_return->desc);
-event_return_error:
- kfree(event_entry->desc->fields);
- kfree(event_entry->desc->name);
- kfree(event_entry->desc);
-error:
- return ret;
-}
-EXPORT_SYMBOL_GPL(lttng_kretprobes_register);
-
-static
-void _lttng_kretprobes_unregister_release(struct kref *kref)
-{
- struct lttng_krp *lttng_krp =
- container_of(kref, struct lttng_krp, kref_register);
- unregister_kretprobe(<tng_krp->krp);
-}
-
-void lttng_kretprobes_unregister(struct lttng_event *event)
-{
- kref_put(&event->u.kretprobe.lttng_krp->kref_register,
- _lttng_kretprobes_unregister_release);
-}
-EXPORT_SYMBOL_GPL(lttng_kretprobes_unregister);
-
-static
-void _lttng_kretprobes_release(struct kref *kref)
-{
- struct lttng_krp *lttng_krp =
- container_of(kref, struct lttng_krp, kref_alloc);
- kfree(lttng_krp->krp.kp.symbol_name);
-}
-
-void lttng_kretprobes_destroy_private(struct lttng_event *event)
-{
- kfree(event->desc->fields);
- kfree(event->desc->name);
- kfree(event->desc);
- kref_put(&event->u.kretprobe.lttng_krp->kref_alloc,
- _lttng_kretprobes_release);
-}
-EXPORT_SYMBOL_GPL(lttng_kretprobes_destroy_private);
-
-int lttng_kretprobes_event_enable_state(struct lttng_event *event,
- int enable)
-{
- struct lttng_event *event_return;
- struct lttng_krp *lttng_krp;
-
- if (event->instrumentation != LTTNG_KERNEL_KRETPROBE) {
- return -EINVAL;
- }
- if (event->enabled == enable) {
- return -EBUSY;
- }
- lttng_krp = event->u.kretprobe.lttng_krp;
- event_return = lttng_krp->event[EVENT_RETURN];
- WRITE_ONCE(event->enabled, enable);
- WRITE_ONCE(event_return->enabled, enable);
- return 0;
-}
-EXPORT_SYMBOL_GPL(lttng_kretprobes_event_enable_state);
-
-MODULE_LICENSE("GPL and additional rights");
-MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
-MODULE_DESCRIPTION("LTTng kretprobes probes");
-MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
- __stringify(LTTNG_MODULES_MINOR_VERSION) "."
- __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
- LTTNG_MODULES_EXTRAVERSION);
projects / lttng-modules.git / blobdiff